Clinical and cost-effectiveness oral abstractsO07. The role of socio-economic factors on the onset of comorbidity in primary care consulters with osteoarthritis: a prospective cohort study

Abstract

Background: Osteoarthritis is the most common joint condition, the fourth leading cause of disability globally and the fastest increasing major health condition. The temporal relationship between osteoarthritis and physical and psychological comorbidity is unclear and may differ by levels of socio-economic status. The aims of this study were to (i) identify if osteoarthritis was associated with the onset of depression, anxiety, cognitive impairment, widespread pain, insomnia, social restriction and neurosis and (ii) determine if these relationships were moderated by education, area level deprivation or change in income. Methods: Prospective cohort study combining questionnaire data at two time points (2005, 2008) and medical record data (n=3910). Osteoarthritis was defined by primary care consultation for osteoarthritis between 2000 and 2005, and the report of moderate/extreme pain interference in the questionnaire (2005). Logistic regression examined the association between osteoarthritis and the onset of seven comorbidities (between 2005 and 2008), first unadjusted and then adjusting for putative confounders (comorbidity, socio-demographic and lifestyle factors). Moderation of the association between osteoarthritis and onset by change in income, education and area-level deprivation was examined by including interaction terms and stratified analyses. Results were reported as odds ratios with a 95% Confidence Interval (OR; 95%CI). Results: Mean age was 63, 55% were female and 942 (24%) had osteoarthritis. In the unadjusted analysis, osteoarthritis was significantly associated with new onset of all seven comorbidities (p<0.05). After adjusting for confounders, osteoarthritis was associated with the onset of depression (OR 1.35; 95%CI 1.02, 1.79), cognitive impairment (1.36; 1.03, 1.81), widespread pain (2.49; 1.96, 3.17) and insomnia (1.58;1.14, 2.19); it was not associated with new onset of anxiety (1.29; 0.97, 1.72), social restriction (1.14; 0.86, 1.49) or neurosis (1.31; 0.86, 1.97). There was a significant non-multiplicative interaction between osteoarthritis and change in income and new onset cognitive impairment (P=0.047), and between osteoarthritis and education and new onset widespread pain (P=0.012). There were no significant interactions between osteoarthritis and change in income, education or area-level deprivation with new onset of depression, anxiety, insomnia, social restriction or neurosis (p>0.05). Conclusion: Consulters for osteoarthritis were more likely to develop new physical and psychological co-morbidities than those without osteoarthritis. While confounders explained some of these associations, osteoarthritis consulters may benefit from more proactive strategies to prevent further morbidity. Despite no significant multiplicative interactions, there were differences in the prevalence of new onset of morbidity in those with osteoarthritis when stratified by socioeconomic status (e.g. onset of cognitive impairment was higher in people with an inadequate income than in those with an adequate income). Osteoarthritis and baseline morbidity were higher in lower socio-economic groups and further exploration across the life course will help to establish the role of socio-economic status in the natural history of osteoarthritis and its impact.